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Abstract
Introduction As the number of female athletes competing rises globally, training methodologies should reflect sex differences across critical metrics of adaptation to training. Surrogate markers of the autonomic nervous system (ANS) used for monitoring training load are heart rate variability (HRV) and resting heart rate (RHR). The aim was to investigate ovarian hormone effects on standard recovery metrics (HRV, RHR, respiratory rate (RR) and sleep duration) across a large population of female athletes.
Methods A retrospective study analysed 362 852 days of data representing 13 535 menstrual cycles (MC) from 4594 respondents (natural MC n=3870, BC n=455, progestin-only n=269) for relationships and/or differences between endogenous and exogenous ovarian hormones on ANS.
Results HRV and return to baseline (recovery) decreased as resting HR and RR increased (p<0.001) from the early follicular to the late luteal phase of the MC. Patterning was paradoxical across phases for users of combined hormonal contraception (BC) as compared with the patterning of the MC. HRV and recovery start elevated and drop off quickly during the withdrawal bleed, rising through the active pill weeks (p<0.001). Progestin-only users had similar patterning as the MC. The relationship between normalised recovery and previous day strain is modulated by birth control type. BC exhibited steeper declines in recovery with additional strain-normalised recovery decreases by an additional 0.0055±0.00135 (p<0.001) per unit of strain; with no significant difference between MC and progestin-only (p=0.19).
Conclusion The patterning of ANS modulation from ovarian hormones is significantly different between naturally cycling women and those on BC, with the patterning dependent on the type of contraception used.
- recovery
- athlete
- female
- performance
- women
Data availability statement
Data are available on reasonable request. The WHOOP data are the property of WHOOP (Boston, Massachusetts, USA). The authors (LW and ERC) are employees of WHOOP and are permitted to access the WHOOP data server. The data are anonymised appropriately; the data used in the study is a backup of the original data and does not include any personally identifiable information.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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Data availability statement
Data are available on reasonable request. The WHOOP data are the property of WHOOP (Boston, Massachusetts, USA). The authors (LW and ERC) are employees of WHOOP and are permitted to access the WHOOP data server. The data are anonymised appropriately; the data used in the study is a backup of the original data and does not include any personally identifiable information.
Footnotes
Contributors STS led the work of the writing group and wrote the manuscript. ERC and LW analysed the data, contributed to the writing and editing. All authors contributed to the design of the study, interpreted the data and critically reviewed the report.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests Two of the authors (ERC, LW) are affiliated to the commercial company WHOOP, however, this does not alter the authors’ adherence to BJSM policies on sharing data and materials.
Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.
Provenance and peer review Not commissioned; externally peer reviewed.